5 points

Earth’s Shape

DATA SHEET

DATA TABLE:Please fill out the table as completely as possible.

ROUNDNESS: 39 points

Object / Equatorial
Diameter / Polar
Diameter / Roundness
Earth / 12,756 km / 12,714 km / 5 points
Blue Globe / 5 points / 5 points / 5 points
White Globe / 5 points / 5 points / 5 points
And the roundest is: ______4 points
SMOOTHNESS:29 points
Measured Relief Globe Height of Mt. Everest:______5 points

Calculated Relief Globe Height of Mt. Everest:______10 points

Percent Deviation of Height of Mt. Everest:______10 points

And the smoothest is: ______4 points

QUESTIONS:Answer questions # 1 – 5 in complete sentences. Answers should not contain any personal pronouns (they, I, them, we, etc.) 3 POINTS EACH

1.

2.

3.

4.

5.

6.ABCD

7.ABCD

8.ABCD

9.ABCD

Lab #3 Earth’s Shape

INTRODUCTION: Please read this as it contains information required to perform the lab and material that may be tested.

Pictures of earth taken from space show that the earth appears to be perfectly round and smooth. However, to us, the earth appears to have a highly irregular surface. In addition, accurate measurements of the earth's shape show that the equatorial diameter is slightly different from the polar diameter. This forms a shape known as an oblate spheroid.

LABORATORY PROCEDURES: Please follow these directions and any directions provided by the instructor. Follow laboratory safety rules at all times.

A. ROUNDNESS

The ratio of the polar diameter to the equatorial diameter of a sphere is a measure of its roundness. Dividing the equatorial diameter by the polar diameter would give a value of one since both diameters are equal in a perfect sphere. The farther from 1 the actual computed ratio is, the less spherical a globe is.

Use the values given for the equatorial and polar diameters of the earth in the data table to calculate the roundness of the earth. Divide the polar diameter into the equatorial diameter. The larger number goes on top, inside, or into the calculator first. Record this value on the data table.

Measure the polar and equatorial diameter of the small, plastic, blue globe. Record these measurements on the data table. Divide the smaller number into the larger number. That means the larger number goes on top, inside, or into the calculator first.

Measure the polar and equatorial diameter of the larger, white, plastic globe. Record these measurements on the data table. Divide the smaller number into the larger number. That means the larger number goes on top, inside, or into the calculator first.

B. SMOOTHNESS:

A relief globe shows the relative height (relief) of its surface features, such as mountains. It is a scale model of the earth. The following procedure will help you determine whether or not these features are constructed to scale. To do this you must use a proportion. Proportions are usually set up like the one below.

Little part of Object ALittle part of Object B

------=------

Big part of Object A Big part of Object B

Measured Relief Globe Height of Mt. Everest: With a ruler, measure the height of Mt. Everest to the nearest tenth of a centimeter on the white, plastic relief globe. Record this number on the data table.

Actual Height of Mt. Everest:8.8 km.

Average Earth Diameter:12740 km

Relief Globe Diameter:Measure the equatorial diameter of the diagram of the relief globe.

Calculated Relief Globe Height of Mt. Everest:Using these values and the proportion shown below, solve the relief globe height of Mt. Everest to correct scale for this diagram of a globe.

Calculated

Actual HeightRelief Globe Height

of Mt. Everest (km.)of Mt. Everest (cm.)

unknown X

------=------

Average Relief Globe

Earth Diameter (km.) Diameter (cm.)

Cross multiply and solve for X by dividing.

Percent Deviation of Mt. Everest: Determine the percent deviation between the height of Mt. Everest on the globe and the height it should have been if drawn to the correct scale. The equation for percent deviation from accepted value is in the Reference Tables.

QUESTIONS: ANSWER QUESTIONS #1 – 5 IN COMPLETE SENTENCES! Answers should not contain any personal pronouns (they, I, them, we, etc.)

3 POINTS EACH

1.What is the name for the true shape of the earth? You may have to read the introduction to come up with this one.

2.What is rounder, the earth or an average classroom globe? Use data from this lab to support your answers.

3.What is smoother, the earth or an average classroom globe? Use data from this lab to support your answers.

4.If the earth were shrunk down proportionately, what would it most resemble, an orange, a pear a billiard (pool) ball, an egg or a Fender Stratocaster with a whammy bar? Why?

5.How do we (humans) know that the earth is somewhat spherical? List at least two ways.

6.Based on the diagram below, what is the circumference of planet X?

A) 18,000 km

B) 9,000 km

C) 24,000 km

D) 36,000 km

7.To an observer on the moon, the Earth in full phase would appear to be shaped like

A) a pear

B) a basketball

C) a football

D) an egg

8.According to the data table below, what is the exact shape of the earth?

Actual Dimensions of the Earth

Equatorial Radius 6,378 km

Polar Radius 6,357 km

Equatorial Circumference40,076 km

Polar Circumference40,008 km

A)slightly flattened at both the Equator and the Poles

B)slightly flattened at the Equator and slightly bulging at the Poles

C)slightly bulging at the both the Equator and the Poles

D)slightly bulging at the Equator and slightly flattened at the Poles

9.The true shape of the Earth is best described as a

A) perfect sphere

B) slightly oblate spheroid

C) very oblate spheroid

D) highly eccentric spheroid